Automated fluid injection devices have gained wide acceptance by the industrial, scientific and medical communities due in large part to the advantages offered by modern data gathering techniques, and consequent reduction in operating manpower without loss in accuracy. Many such devices are capable of dispensing very small, accurately measured quantities of fluid specimens on the order of a few microliters, or very small fractions of a microliter, e.g., from about 0.01 to about 5 microliters, or fractional parts thereof into of a medium. One such type of fluid injector device can be characterized as an automated syringe, e.g., as described in U.S. Pat. No. 4,044,616. In the operation of the automated syringe, septum covered vials charged with portions of a fluid specimen are transported via a magazine to a station adjacent a probe assembly, the probe assembly picks up a specimen from a vial and a portion of the fluid specimen is conveyed via action of the probe assembly to the barrel of the syringe. Within the barrel of the syringe, a quantity of the fluid specimen is measured out and injected into the inlet of the analytical instrument.
Albeit very small quantities of fluid specimens can be measured out within the barrel of the syringe, and accurately injected, there is considerable impetus to further increase the capability of fluid injection devices to measure out and inject smaller, and yet smaller amounts of a fluid specimen with accuracy and precision.
Another class of fluid injection devices which has been used for measuring out and injecting small amounts of a fluid specimen with accuracy and precision into a medium are capillary dippers, or capillary injection devices. These devices differ as a class from syringes principally in that the fluid specimen is loaded via capillary action to a capillary opening of calibrated volume located on the terminal end of a probe. The measured quantity of the fluid specimen is injected not generally by positive displacement means but by insertion of the dispensing end of the probe into an inlet to an analytical instrument, and the fluid is flashed out of the calibrated opening, and conveyed by carrier gas to the instrument. The development of capillary injection devices, albeit these devices are particularly useful for measuring out and injecting very, very small quantities of a fluid specimen with accuracy and precision, has been far slower than that of automated syringes. There is indeed a particular need for the development of new and improved capillary fluid injectors, particularly automated capillary fluid injectors.